The effects of experimental applied to different doses lead-acetate in rats on arginase activity and kinetic properties of the arginase enzyme

2. ABSTRACT THE EFFECTS OF EXPERIMENTAL APPLIED TO DIFFERENT DOSES LEAD-ACETATE IN RATS ON ARGINASE ACTIVITY AND KINETIC PROPERTIES OF THE ARGINASE ENZYME In the city life and the industrial branches which lead is used, an exposure to lead occurs and as a consequence acute or chronic poisonings are observed. Nowadays, in rural regions few mg of leads are taken with food and water. The lead spreading from the industrial wastes and exhaust of the motor vehicles has an effect on creatures. The lead exposure affects all society and causes various health problems. Arginase which is the last enzyme of the urea cycle ( L-arginine urea hydrolase or amidohydrolase (E.C 3.5.3.1) is responsible for the detoxification of the liver and ammoniac in mammals by hydrolyzing arginine to ornithine and urea. The liver is the organ which has the highest arginase activity. Its activity in extra-hepatic tissues is distinctly lower than liver. We have examined the effect of the lead acetate on the arginase activity found in the liver tissues. In the experiment, 28 Wistar type albino rats were used with the weight of 250 +/- 50 grams and approximately 8 weeks old. The samples were randomly taken and divided into four groups. The groups are regulated as follows; Group I: control group 1 ml physiological saline solution i.p, Group II. Lead acetate 25 mg/kg-i.p Group III: Lead acetate 50 mg/kg-i.p Group IV: lead acetate 75 mg/kg- ip The lead acetate has been added into 1 ml physiological saline solution and during 7 days it was applied in peritoneum one per night and day. At the end of the experiment 10 mg/kg peritoneal spread was applied into 75 mg/kg+ xylazine to the rats in all groups under the anesthesia. Following the decapitation, the liver tissues of the rats are displaced rapidly and were washed with % 0,9 NaCI and were storage in deep freezer at 80 °C C by being packaged and taken to laboratory in cold chain. The preincubation temperature for rat liver tissues was determined as 65 °C and the preincubation time as 20 minutes , incubation time as 18 minutes and optimum pH as 10. The enzyme has given the highest activity in 3 mM MnCI2 concentration. As the result, it is determined that Mn+2 ions and preincubation at 65 °C is required for the activation of the enzyme. It is observed that Km of the rat liver which is opposite to L-arginine of tissue arginase including lead is approximately 8,5 mM and control group is approximately 11,5 mM. As the result, it is observed that Km and Vmax in the presence of Pb causes uncompetitive inhibition by decrasing. Key Words: Lead acetat, Arginase, Rats